Both Ser. No. 07/474,556 and Ser. No. 07/474,555 disclose a row-interleaved printing method for use in phase change (also referred to as thermoplastic or hot melt) ink jet printers of the drop-on-demand (also known as impulse) and continuous types. The interleaving (also called interlacing) method disclosed in these related applications is intended to minimize appearance abnormalities when printing solid geometric shapes; minimize the horizontal "banding-effect" caused by cross-talk between ink jets when all jets are activated; and minimize the "seaming effect" caused by paper step mechanisms when different velocity profiles are used during printing. This is achieved by meeting the three following guidelines:
1) Adjacent dot rows should not be laid down in the same pass. PA1 2) Each dot row should be sandwiched by either (a) virgin paper on both sides of the dot row, or (b) ink on both sides of the dot row. If a dot row is laid down with ink on one side and virgin paper on the other side, non-uniformity would be the result. PA1 3) The first and the last dot row in each solid pattern are exempted from guidelines #2 and #3. PA1 1) Guideline #1 is to prevent adjacent dot rows to fuse together forming a band of dots per pass. PA1 2) Guideline #2 is to maintain thermal symmetry within a solid pattern. PA1 3) The first and the last dot row of each printed pattern is exempted from the symmetry requirement because these rows represent the transition from one color to another and therefore do not have to be uniform or symmetrical on both sides of the dot row.
The following are the reasons behind the above guidelines: